Reaction entropy measurements for transition-metal ions bound to nation-coated electrode surfaces

Charles M. Lieber, Michael H. Schmidt, Nathan S Lewis

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Reaction entropies, ΔS°rc, have been determined for a series of transition-metal ions electrostatically bound into Nafion films. Complexes with hydrophobic, "shielding" ligands such as Ru(2,2′-bipyridine)3 3+/2+ and Co(2,2′-bipyridine)3 3+/2+ yield similar ΔS°rc values in Nafion films and in aqueous solution, indicating that the electrochemically active probes reside in a predominantly waterlike local environment in the polymer film. Complexes containing aquo and ammine ligands yield markedly lower ΔS°rc values in Nafion than in aqueous media (μ = 0.1 M). The ΔS°rc values for these Nafion-bound systems are similar to values measured for the Ru(NH3)6 3+/2+ system in concentrated aqueous salt solutions (5 M LiCl). The ΔS°rc measurements imply that the outer-sphere electron-transfer work terms for polymer bound ions may be lower than those observed in typical aqueous solutions. Differential free energies, enthalpies, and entropies of transfer for the redox reaction M(III) + e- → M(II) from aqueous media to Nafion have also been determined.

Original languageEnglish
Pages (from-to)1002-1003
Number of pages2
JournalJournal of Physical Chemistry
Volume90
Issue number6
Publication statusPublished - 1986

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Transition metals
Metal ions
metal ions
Entropy
transition metals
entropy
Electrodes
electrodes
Ligands
ammines
aqueous solutions
ligands
Redox reactions
polymers
Polymer films
Shielding
Free energy
shielding
Enthalpy
electron transfer

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Reaction entropy measurements for transition-metal ions bound to nation-coated electrode surfaces. / Lieber, Charles M.; Schmidt, Michael H.; Lewis, Nathan S.

In: Journal of Physical Chemistry, Vol. 90, No. 6, 1986, p. 1002-1003.

Research output: Contribution to journalArticle

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